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Offstream
use: Water withdrawn
or diverted from a ground- or surface-water source for public-water supply,
industry, irrigation, livestock, thermoelectric power generation, and other
uses. Sometimes called off-channel use or withdrawal.
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Oligotrophic: Having a low
supply of plant nutrients. Compare eutrophic.
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Oligotrophic
lake: Deep, clear
lakes with low nutrient supplies. They contain little organic matter and have
a high dissolved oxygen level.
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Once-through cooling water:
Water (fresh or saline)
that is withdrawn from a river, stream or other water body (manmade or natural),
or a well, that is passed through a steam condenser one time, and then returned
to the river or stream or other water body some distance from the intake. Once-through
cooling water is used to exchange the heat from the steam condensers to the
cooler water.
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Open system: System in which
energy and matter are exchanged between the system and its environment, for
example, a living organism.
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Organic: (1) Referring
to or derived from living organisms. (2) In chemistry, any compound containing
carbon.
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Organic
chemicals: Chemicals
containing carbon.
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Organic
matter: Substances
of (dead) plant or animal matter, with a carbon-hydrogen structure.
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Organism: A living thing.
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Orogeny: Period of mountain-building.
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Orographic
precipitation:
Rainfall that occurs as
a result of warm, humid air being forced to rise by topographic features such
as mountains. Precipitation on the edwards plateau is slightly higher because
of the orographic effect of the escarpment and hills.
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Osmosis: Water molecules
passing through membranes naturally, to the side with the highest concentration
of dissolved impurities.
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Other water
use: Water used
for such purposes as heating, cooling, irrigation (public-supplied only), lake
augmentation, and other nonspecific uses. The water can be obtained from a public
supply or be self-supplied.
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Outcrop: Exposed at the
surface. The edwards limestone outcrops in its recharge zone.
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Outfall: The place where
a wastewater treatment plant discharges treated water into the environment.
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Outfall: The place where
a wastewater treatment plant discharges treated water into the environment.
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Outwash: A deposit of
sand and gravel formed by streams of meltwater flowing from a glacier.
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Overflow
rate: One of
the guidelines for design of the settling tanks and clarifiers in a treatment
plant to determine if tanks and clarifiers are used enough.
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Oxidation: A chemical reaction
in which ions are transferring electrons, to increase positive valence.
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Oxidation
pond: A man-made
body of water in which waste is consumed by bacteria.
-
Oxidation-reduction
potential: The
electric potential required to transfer electrons from the oxidant to the reductant,
used as a qualitative measure of the state of oxidation in water treatment systems.
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Oxygen demanding
waste: Organic
water pollutants that are usually degraded by bacteria if there is sufficient
dissolved oxygen (DO) in the water.
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Oxygen depletion: The reduction
of the dissolved oxygen level in a water body.
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Ozonation: A new technology
using a form of oxygen, instead of chemicals, to treat cooling water.
-
Ozone: An unstable oxidizing
agent, that consists of three oxygen atoms and can be found in the ozone layer
in the atmosphere. It is produced by electrical discharge through oxygen or
by specifically designed UV-lamps.
-
Ozone generator: A device that
generates ozone by passing a voltage through a chamber that contains oxygen.
It is often used as a disinfection system.
